How much is the upper limit of video capacity when we use Video Editing?
Blender has the frame number limit.

Working Limits : Time


  "The maximum number of frames for each scene is currently 1,048,574,
  and allows for continuous shots for durations of:
  
  24 fps:   12 hours, 8 seconds.
  
  25 fps:   11 hours, 39 seconds.
  
  30 fps:   9 hours, 42 seconds.
  
  60 fps:   4 hours, 51 seconds."


But in your case this could be insufficient RAM as well.